Interesting facts about roasting coffee beans
On which tree do the beans for espresso, cappuccino or café au lait grow? An important question that coffee lovers ask themselves. However, it is not the type of coffee that is decisive for the later method of preparation, but the roast. In addition to the type of preparation, the roasting process also determines the subsequent aroma of the coffee: Roast the coffee and achieve the best result!
Roasting process: transformation of the coffee bean
Coffee roasting is as diverse as the range of coffee beans. The processes and devices used are as different as the different coffees that are made from them. Roasting coffee means giving it your very own, unmistakable character. This applies regardless of whether the green coffee is Arabica, Robusta or a mixture of several varieties from different growing areas. Coffee is transformed into a food by roasting, which is then available for one of the many enjoyable preparation methods.
The roasting process sets several important processes in motion. The heat causes the beans to lose water and, with it, weight. At the same time, their volume increases due to the formation of water vapor due to the slowly rising temperature. This chemical process takes place as a chain reaction and leads to the typical, different coffee aromas. The sugar contained in the beans caramelizes at around 160 ° C to 190 ° C. Between 165 ° C and 210 ° C, the roasted aroma is created by the Maillard reactions. The connection of sugars such as glucose and lactose with amino acids creates new flavors.
The maximum temperature and heat curve are of central importance in the roasting process. Drum roasting or hot air roasting (industrial roasting), airflow and chimney when roasting the coffee bean are some of the factors that affect the taste of the coffee that will be prepared later. So it’s no wonder that the roasting curve is often a well-guarded trade secret.
Different roasting methods
The way it is roasted determines the taste of the coffee that will be made later. The principle that long roasting leads to a better taste and a more pronounced aroma continues to apply. However, this technique, which is preferred by small roasting companies, is not necessarily better than industrial roasting: there, too, drum roasters are still in use, which are preferably used for roasting small quantities of coffee beans.
The traditional drum roasting usually takes eight to 25 minutes and reaches temperatures between 180 ° C and 240 ° C. The amount of coffee produced varies between 30 kilograms in shop roasters and over 600 kilograms in larger systems. With drum roasting, the externally heated drum with notches rotates around its own center to swirl the coffee beans. Internal heating with a fan is also conceivable in order to keep the temperature in the entire drum at the same level. The slow roasting is enough time for the coffee beans to develop flavors and reduce unwanted acids.
The industrial coffee roasting takes about two to seven minutes. The coffee beans are roasted in the order of 250 to 600 kilograms. The work is done with hot air between 400 ° C and 800 ° C, which can create undesirable, even burnt, roasted aromas. The coffee bean is beautifully brown on the outside, but on the inside, it cannot be “done” yet.
In comparison: With drum roasting, the temperature curve is much flatter, and the final temperature is not as high as with industrial hot air roasting. When the beans have reached the desired maximum heat, they then cool down on a sieve. This takes much longer than roasting and sometimes cold air or even water cooling is used, especially for industrial roasting. However, one should pay attention to the following: the coffee bean should not absorb too much moisture after roasting.
The degree of roasting determines the taste
A fundamental distinction when roasting coffee is between light and dark. The light roast leads to grassy or bread-like aromas, so it emphasizes the acidity. This roasting process is recommended for filter coffee, for example. The dark roast takes longer and goes to a higher temperature level. This leads to less acidity and more bitter substances in the coffee that is created from it. These beans are mainly used for espresso.
When mixing different types of coffee, there are two methods of roasting. The varieties are roasted separately and only then mixed. The roasting process is individually tailored to the different types, but the subsequent mixture creates different extraction profiles. If the coffee is mixed before roasting, such as in industrial roasting, the taste is more balanced. However, it is important to ensure that the coffee beans have a certain balance in terms of size, hardness and degree of moisture. Otherwise, some of the ingredients are not yet roasted – while others have already been “burnt”.
Nice anecdotes about coffee roasting
Coffee has been part of human cultural history for around 1000 years. It began on the high plateaus in the East African Ethiopia. So it’s no wonder that there are so many myths and anecdotes about it. For example this story about the first, unintentional roasting of green coffee. It is the story of the shepherd whose goats get the red fruits from a particular tree. After that, they stayed very active all night. The shepherd looked for an explanation for this behavior and showed some of the red cherries to the abbot of the nearby monastery. He thought it was the work of the devil and threw it into the fire. There they developed such a seductive scent that the monks put out the fire. This is how delicious coffee was created from the extinguishing water from the first, unplanned and unconscious roast.
Conclusion: freshly roasted – maximum enjoyment
The most important thing that the connoisseur takes away from the article about coffee roasting is the insight: Freshly roasted coffee beans, which are then ground without much loss of time and, for example, made into espresso or café au lait, unfold the greatest pleasure. Regardless of which coffee you ultimately choose from among the many preparation methods: it always tastes best from the fresh roast.